[bell rings] >> on tuesday morning, president obama, first lady michelle obama, and the white house staff gathered on the south lawn of the white house for a moment of silence to honor the victims of the 9/11 terrorist attacks. [bell rings] [playing "taps"] >> and the pentagon held its own memorial service on tuesday. president obama, defense secretary leon panetta, and joint chiefs of staff martin dempsey took part in the ceremony, honoring those injured in the attack. >> good morning. thank you for being here. we offer a special welcome to the family and friends of those we lost 11 years ago today. one of them was the chief warrant officer. his bench was seventh in from the far right. he served as a marine in vietnam, flying helicopters. joined the army national guard as a medac pilot. he was loved by his students and moved by his deep commitment to them. one student said, he opened up my eyes and by heart to the world. many others became teachers, nurses, firefighters. bill retired from the classroom and return to serve in the pentagon. there is no doubt he lost his life that morning b